Mechanical Engineering Gate 2013 Set-4 Questions with Answer

Ques 53 GATE 2013 SET-4


Two threaded bolts A and B of same material and length are subjected to identical tensile load. If the elastic strain energy stored in bolt A is 4 times that of bolt B and the mean diameter of bolt A is 12 mm, the mean diameter of bolt B in mm is

A

16

B

24

C

36

D

48


(b) is the correct answer.

Ques 54 GATE 2013 SET-4


A simply supported beam of length L is subjected to a varying distributed load sin(3πx/L) Nm-1, where the distance x is measured from the left support. The magnitude of the vertical reaction force in N at the left support is

A

zero

B

L/3π

C

L/π

D

2L/π


(b) is the correct answer.

Ques 55 GATE 2013 SET-4


If two nodes are observed at a frequency of 1800 rpm during whirling of a simply supported long slender rotating shaft, the first critical speed of the shaft in rpm is

A

200

B

450

C

600

D

900


(b) is the correct answer.

Ques 56 GATE 2013 SET-4


A planar closed kinematic chain is formed with rigid links PQ = 2.0 m, QR = 3.0 m, RS = 2.5 m and SP = 2.7 m with all revolute joints. The link to be fixed to obtain a double rocker (rocker-rocker) mechanism is

A

PQ

B

QR

C

RS

D

SP


(c) is the correct answer.

Ques 57 GATE 2013 SET-4


A link OB is rotating with a constant angular velocity of 2 rad/s in counter clockwise direction and a block is sliding radially outward on it with an uniform velocity of 0.75 m/s with respect to the rod, as shown in the figure. If OA = 1 m, the magnitude of the absolute acceleration of the block at location A in m/s2 is

A

3

B

4

C

5

D

6


(c) is the correct answer.

Ques 58 GATE 2013 SET-4


A flywheel connected to a punching machine has to supply energy of 400 Nm while running at a mean angular speed of 20 rad/s. If the total fluctuation of speed is not to exceed ±2%, the mass moment of inertia of the flywheel in kg-m2 is

A

25

B

50

C

100

D

125


(a) is the correct answer.

Ques 59 GATE 2013 SET-4


A cylinder contains 5 m3 of an ideal gas at a pressure of 1 bar. This gas is compressed in a reversible isothermal process till its pressure increases to 5 bar. The work in kJ required for this process is

A

804.7

B

953.2

C

981.7

D

1012.2


(a) is the correct answer.

Ques 60 GATE 2013 SET-4


The pressure, dry bulb temperature and relative humidity of air in a room are 1 bar, 30°C and 70%, respectively. If the saturated steam pressure at 30°C is 4.25 kPa, the specific humidity of the room air in kg water vapour/kg dry air is

A

0.0083

B

0.0101

C

0.0191

D

0.0232


(c) is the correct answer.

Ques 61 GATE 2013 SET-4


The pressure, temperature and velocity of air flowing in a pipe are 5 bar, 500 K and 50 m/s, respectively. The specific heats of air at constant pressure and at constant volume are 1.005 kJ/kgK and 0.718 kJ/kgK, respectively. Neglect potential energy. If the pressure and temperature of the surroundings are 1 bar and 300 K, respectively, the available energy in kJ/kg of the air stream is

A

170

B

187

C

191

D

213


(c) is the correct answer.

Ques 62 GATE 2013 SET-4


Specific enthalpy and velocity of steam at inlet and exit of a steam turbine, running under steady state, are as given below:

Specific enthalpy (kJ/kg)Velocity (m/s)
Inlet steam condition3250180
Exit steam condition23605

The rate of heat loss from the turbine per kg of steam flow rate is 5 kW. Neglecting changes in potential energy of steam, the power developed in kW by the steam turbine per kg of steam flow rate, is

A

901.2

B

911.2

C

17072.5

D

17082.5


(a) is the correct answer.

Ques 63 GATE 2013 SET-4


In a simple Brayton cycle, the pressure ratio is 8 and temperatures at the entrance of compressor and turbine are 300 K and 1400 K, respectively. Both compressor and gas turbine have isentropic efficiencies equal to 0.8. For the gas, assume a constant value of cp (specific heat at constant pressure) equal to 1 kJ/kgK and ratio of specific heats as 1.4. Neglect changes in kinetic and potential energies.

The power required by the compressor in kW/kg of gas flow rate is

A

194.7

B

243.4

C

304.3

D

378.5


(c) is the correct answer.

Ques 64 GATE 2013 SET-4


In a simple Brayton cycle, the pressure ratio is 8 and temperatures at the entrance of compressor and turbine are 300 K and 1400 K, respectively. Both compressor and gas turbine have isentropic efficiencies equal to 0.8. For the gas, assume a constant value of cp (specific heat at constant pressure) equal to 1 kJ/kgK and ratio of specific heats as 1.4. Neglect changes in kinetic and potential energies.

The thermal efficiency of the cycle in percentage (%) is

A

24.8

B

38.6

C

44.8

D

53.1


(a) is the correct answer.

Ques 65 GATE 2013 SET-4


A single degree of freedom system having mass 1 kg and stiffness 10 kN/m initially at rest is subjected to an impulse force of magnitude 5 kN for 10-4 seconds. The amplitude in mm of the resulting free vibration is

A

0.5

B

1.0

C

5.0

D

10.0


(c) is the correct answer.

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